1. Field of the Invention
The present invention relates to a liquid crystal cell having particulate material for establishing the distance between substrates and disposed on an internal surface of one of the transparent substrates between which is sealed a liquid crystal material.
2. Description of the Prior Art
FIG. 3 shows a schematic drawing in cross-section of a conventional liquid crystal cell in the configuration of a dot matrix display type wherein a liquid crystal material 2 is sealed between transparent glass substrates 1,1 with a sealing material 3. Particles 4 of particulate material for spacing the transparent substrates 1,1 are disposed over the entire internal surface of one of the transparent glass substrates 1,1.
In the liquid crystal cell of such conventional construction, the particles 4 of particulate material for such spacing are uniformly disposed between the transparent glass substrates 1,1; hence, the spacing or distance between the glass substrates 1,1 is at a uniform value. If it is assumed that the particles 4 of particulate material are solid bodies, such as glass fiber chips, the spacing or distance accuracy between the substrates 1,1 will be of from about .+-.0.1 to 0.2 .mu.m. Specifically, in the liquid crystal cell of the dot matrix display type, a spacing or distance accuracy of .+-.0.1 to 0.2 .mu.m is necessary to obtain the prescribed electro-optional characteristics; therefore, it is useful to use solid bodies having uniform outside diameters (like glass fiber chips) as the particles 4 of particulate material.
In the conventional liquid crystal cell, particles 4 of particulate material for spacing the substrates are uniformly scattered over the entire surface of transparent glass plate 1. Consequently, in an automobile-use crystal cell, for instance, where storage temperatures may reach as low as -40.degree. C., vacuum bubbles 5 (spaces in a vacuum state), referring to FIG. 4, pose a problem. Namely, at a low temperature of about -40.degree. C., liquid crystal material 2 sealed between the transparent glass substrates 1,1 contracts and reduces in volume. The transparent glass substrate 1 can not deflect inwardly because the particles 4 of particulate material for spacing are comprised of the solid bodies which are disposed over an entire surface thereby permitting the formation of vacuum bubbles 5.
Further, if the quantity of particles 4 of particulate material for spacing the substrates is reduced, i.e. distance between the particles 4 of particulate material increases which widens the spacing between particles 4 of particulate material, the transparent glass substrate 1 may deflect inwardly. In such case, however, pressure applied to the respective particles 4 of the particulate material during the pressurizing-heating process (reduction in quantity results in application of higher pressure to each particle 4 of particulate material), certain particles 4 of the particulate material are caused to disintegrate, thereby posing a problem of failure to maintain uniform spacing accuracy between substrates 1,1.